My daughter and I went in December last year. It is the most beautiful, magical experience but I have to say that it was bitterly cold - I can't ever remember being so cold. At weekends the crowds were horrendous but markedly less so in the week. We are going on 6th November this year and hope to get all the benefits without freezing to death!! The show in Fantasyland, by the way, is nice but I wouldn't say your holiday will be less enjoyable for missing one show. But, yes, it's certainly well worth going in the Christmas season - it's really beautiful and the Enchanted Fairytale Ceremony is absolutely wonderful - get a good spot at the front if you can - it makes a big difference.